Why Does a Bimetallic Strip Bend When Cooled?

When the temperature is decreased the metal low coefficient of thermal expansion will bend towards the other. When the bimetallic strip is heated, the metal with higher thermal expansion will bend more. Thus they bend towards the metal having a lower thermal expansion.

What happens when a bimetallic strip is cooled?

When this bimetallic strip is heated, the brass expands more than the steel and the strip curves with the brass on the outside. If the strip is cooled, it curves with the steel on the outside. Bimetallic strips are used as switches in thermostats.

Which way does a bimetallic strip bend when cooled?

The different expansions force the flat strip to bend one way if heated, and in the opposite direction if cooled below its initial temperature. The metal with the higher coefficient of thermal expansion is on the outer side of the curve when the strip is heated and on the inner side when cooled.